1. Field of the Invention
This invention relates to a refrigerator including a cold storage zone evaporator, a freezing zone evaporator, a first passage through which refrigerant is caused to flow into the cold storage zone evaporator and a second passage through which the refrigerant is caused to flow into the freezing zone evaporator, the first and second passages being in parallel with each other.
2. Description of the Related Art
There have conventionally been provided household refrigerators having a cold storage zone 1 and a freezing zone 2 as shown in FIG. 18. The zones 1 and 2 are divided by a heat insulation partition wall 3. The cold storage zone 1 is further divided by a partition plate 4 into an upper cold storage compartment 1a and a lower vegetable compartment 1b. Only a freezing compartment 2a is defined in the freezing zone 2.
A cold storage component compartment 5 is defined deep in the vegetable compartment 1b in the cold storage zone 1. An evaporator 6, a fan 7 and an electric heater 8 all for the cold storage zone are disposed in the cold storage component compartment 5. A refrigerating component compartment 9 is defined deep in the freezing compartment 2a in the freezing zone 2. An evaporator 10, a fan 11 and an electric heater 12 are also disposed in the freezing component compartment 9. Air in the cold storage zone 1 is circulated by the fan 7 while in contact with the evaporator 6, as shown by arrows in FIG. 18. Air in the freezing zone 2 is also circulated by the fan 11 while in contact with the evaporator 10, as shown by arrows in FIG. 18. Thus, both fans 7 and 11 are for air circulation in the refrigerator. The heater 8 dissolves frost adherent to the evaporator 6 thereby to remove the frost. The heater 12 also dissolves frost adherent to the evaporator 10 thereby to remove the frost. Thus, the heaters 8 and 12 are for defrosting. A machine compartment 13 is provided in a lowest rear of the refrigerator. A compressor 14 is disposed in the machine compartment 13.
FIG. 19 shows an exemplified arrangement of equipment composing a refrigerating cycle for the foregoing refrigerator. A refrigerant is circulated through the equipment so that the refrigerating cycle is carried out. In the shown refrigerating cycle, the two evaporators are individually provided for the cold storage and freezing zones 1 and 2 respectively and connected in parallel with each other. The refrigerant is compressed by the compressor 14 into a high-temperature high-pressure gas, which enters a condenser 15. The condenser 15 is cooled by a heat-dissipating fan (not shown) such that the refrigerant is cooled into an ordinary temperature high-pressure liquid. The liquefied refrigerant is introduced from the condenser 15 into a three-way valve 16 having one entrance and two exits. A capillary tube 17 for the cold storage zone is connected to one of the exits, whereas a capillary tube 19 for the freezing zone is connected to the other exit. The valve 16 switches the direction of the refrigerant between a case where an atmosphere in the cold storage zone 1 is cooled and a case where an atmosphere in the freezing zone 2 is cooled.
FIG. 20 shows a flow of the refrigerant by way of arrows in the case where the atmosphere in the cold storage zone 1 is cooled. In this case, the refrigerant flowing out of the condenser 15 enters the cold storage zone capillary tube 17 by the switching of the valve 16. The refrigerant passes through the capillary tube 17 to be introduced into the cold storage zone evaporator 16. The capillary tube 17 reduces the pressure of an ordinary temperature high-pressure liquid refrigerant so that the refrigerant fed to the evaporator 16 is easily evaporated. The capillary tube 17 also controls a flow rate of the liquid refrigerant. The refrigerant having entered the evaporator 6 evaporates into a gaseous refrigerant. During evaporation, an ambient heat is absorbed so that the evaporator 6 is cooled. The cold storage zone fan 7 is operated so that air in the cold storage zone 1 is circulated while in contact with the cooled evaporator 6, whereupon the atmosphere in the cold storage zone 1 is cooled. The liquid refrigerant evaporates in the evaporator 6 into gaseous refrigerant, which is returned through a suction pipe 18 into the compressor 14 to be re-compressed.
On the other hand, the refrigerant flows through a path as shown by arrows in FIG. 21 when the atmosphere in the freezing zone 2 is cooled. More specifically, the refrigerant flowing out of the condenser 15 further flows through the three-way valve 16 into a capillary tube 19 for the freezing zone. The refrigerant further flows through the capillary tube 19 into the freezing zone evaporator 10. In the evaporator 10, the refrigerant evaporates into a gaseous refrigerant. The evaporator 10 is cooled during the evaporation. Thereafter, the refrigerant returns through a check valve 20 and the suction pipe 18 into the compressor 14. An accumulator (not shown) may or may not be provided between the freezing zone evaporator 10 and the check valve 20. Thus, the refrigerating cycle as shown in FIG. 19 has a passage through which the refrigerant flows so that the atmosphere in the cold storage zone is cooled and a passage through which the refrigerant flows so that the atmosphere in the freezing zone is cooled, both passages being in parallel with each other. The three-way valve 16 switches between the passages.
A temperature in the freezing zone 2 is required to be lower than a temperature in the cold storage zone 1. For this purpose, an evaporating temperature at which the refrigerant evaporates in the freezing zone evaporator 10 should be lower than an evaporating temperature at which the refrigerant evaporates in the cold storage zone evaporator 6. An evaporating pressure needs to be reduced in order that the evaporating temperature of the refrigerant may be reduced. Accordingly, the freezing zone capillary tube 19 is throttled more than the cold storage zone capillary tube 17 so that the refrigerant having passed through the capillary tube 19 evaporates at a lower pressure and a lower temperature. The check valve 20 prevents the refrigerant from flowing into the freezing zone evaporator having a lower temperature to be re-condensed.
On the other hand, conventional refrigerators have been provided including a single evaporator used to cool both the cold storage and freezing zone evaporators although not shown in the drawings. Other conventional refrigerators have further been provided including two evaporators for the cold storage zone and freezing zones respectively, although the evaporators are not shown in the drawings. The evaporators are connected in series to each other. In these conventional refrigerators, atmospheres in both of the cold storage and freezing zones are cooled simultaneously.
However, in the foregoing refrigerators with parallel connected evaporators 6 and 10, the valve 16 is switched so that the refrigerant flows selectively through one of the evaporators 6 and 10. Accordingly, the atmospheres in the cold storage and freezing zones 1 and 2 are only cooled alternately. Accordingly, when electric power is supplied to the refrigerator with its interior not being sufficiently cooled, it takes a long time to cool the interiors of the compartments in both cold storage and freezing zone 1 and 2 so that respective set temperatures are reached. For the purpose of solving this problem, the refrigerant is caused to flow simultaneously into both evaporators while atmospheres in the compartments are not sufficiently cooled. In this case, however, since an amount of refrigerant circulated is increased, there are possibilities that the compressor 14 may be overloaded, that the temperature of the condenser 15 may be increased excessively, that a cooling operation for either one of the cold storage and freezing zones 1 and 2 may be retarded relative to the other to a large extent, and so forth.
Therefore, an object of the invention is to provide a refrigerator in which a refrigerating cycle includes two parallel connected passages through which the refrigerant flows into the cold storage zone evaporator and the freezing zone evaporator respectively and in which atmospheres in both the cold storage and freezing compartments can be cooled as quickly as possible without the refrigerating cycle being overloaded and without any other problems so that predetermined temperatures are reached in the cold storage and freezing zones respectively, after power supply to the refrigerator.
To achieve the object, the present invention provides a refrigerator provided with a cold storage zone and a freezing zone both defined therein, comprising a compressor for compressing a refrigerant, a condenser provided with a heat-dissipating fan, a first passage including a cold storage zone capillary tube and a cold storage zone evaporator, the latter two being connected in series to each other, a second passage including a freezing zone capillary tube and a freezing zone evaporator, the latter two being connected in series to each other, a switching valve causing the refrigerant condensed by the condenser to flow selectively through any one of the first passage, the second passage and both the first and second passages, a variable speed, cold storage zone fan circulating air in the cold storage zone while the air is in contact with the cold storage zone evaporator, a variable speed, freezing zone fan circulating air in the freezing zone while the air is in contact with the freezing zone evaporator, and control means. The control means switches the switching valve upon power supply to the refrigerator so that the refrigerant flows through both the first and second passages. The control means starts the cold storage zone fan so that said fan is driven at a high speed. The control means further starts the freezing zone fan so that said fan is driven at a lower speed than the cold storage zone fan and the heat-dissipating fan so that an operation in which atmospheres in both the cold storage and freezing zones are simultaneously cooled is continued until a temperature or temperatures in the cold storage and/or freezing storage zone decreases to a value or values smaller than a predetermined value or values, respectively or until a predetermined period of time elapses after the power supply to the refrigerator. The control means thereafter executes a normal operation mode.
Upon power supply to the refrigerator, the refrigerant flows through both the first and second passages. Accordingly, both the cold storage and freezing zones are simultaneously cooled. Furthermore, since rotational speeds of the cold storage and freezing zone fans are adjusted, the refrigerating cycle can be prevented from an overloaded condition and the atmospheres in both zones can be cooled for substantially the same period of time so that the respective set temperatures are reached.